Cyclo-octadiene iron subgroup metal carbonyls



Patented Jan. 5, l fi 3,164,621 CYCLO-GCTADIENE lRON SUBGROUP lWETAL CARBGNYLS Kryn G. Erman, Gal: Park, and Thomas'H. Coffield,

Farmington, Mich, assignors to Ethyl Corporation, New York, N.Y., a corporation of Virginia No Drawing. Filed Apr. 12, 1963, Ser. No. 272,528

- 5 Claims. ((31. 260-439) This invention relates to novel organometallic compounds and their mode of preparation. More specifically, this invention relates to cyclooctadiene iron-subgroup metal tricarbonyls wherein the metal atom is bonded to a cyclooctadiene molecule and in addition is bonded to three carbonyl groups.

It is an object of this invention to provide a novel class of cyclooctadiene transition metal carbonyl compounds. A further object is to provide a process for the preparation of these compounds. Additional objects of this invention will become apparent from a reading of the specification and claims which follow.

The objects of this invention are accomplished by providing compounds represented by the' following formula:

wherein Q is a cyclooctadiene molecule and M is an ironsubgroup metal. In the new compounds of this invention, the cyclooctadiene molecule, represented by Q, donates four electrons to the metal atom M, and each carbonyl group donates two electrons to the metal atom. By virtue of the electrons donated to the metal atom, it achieves an electron configuration equivalent to the elec tron configuration of the next higher inert gas in the Periodic Table; i

The cyclooctadiene molecule Q, is 1,5-cyclooctadiene. The cyclooctadiene is substituted with 12R groups which may be the same or different and are selected from the I group consisting of hydrogen and monovalent hydrocarbon radicals containing from one to about eight carbon atoms. Typical monovalent hydrocarbon radicals are alkyl, aryl, cycloalkyl, alkenyl, cycloalkenyl, aralkyl and alk'aryl radicals. Typical radicals are methyl, propyl, phenyl, tert-butyl, p-chlorophenyl, neo-pentyl, chloro methyl, octyl, cyclohexyl, propenyl, cyclopentyl, cyclopentenyl, cyclopropyl, 2-methyl-2-butenyl, cyclohexenyl,

- benzyl, Z-phenylethyl, p-ethylphenyl, 2,4-dimethylphenyl and tolyl.

Preferred substituent groups, R, are hydrogen and monovalent aliphatic hydrocarbon groups containing from one to about eight carbon atoms. It is further preferred that the sum of the carbon atoms in all of the R substituent groups does not exceed about ten. It is found that when this preference is satisfied, the compounds have superior physical characteristics rendering them of greatest utility as additives to hydrocarbon fuels.

The metaLll/I, in the above formula is an iron-subgroup metal. Thus, the metal is selected from the class consisting of iron, ruthenium and osmium. Iron is a particularly preferred metal since compounds of this metal are generally more stable than the analogous osmium and ruthenium compounds.

Typical compounds of this invention are 3-octyl-7- ethyl-1,5-cyclooctadiene iron tricarbonyl, 2-ethyl-l,5- c'yclooctadiene iron tricarbonyl, 3-n1ethy1- L5-cyclooctadiene iron tricarbonyl, Z-cyclopropyl-1,5-cyclooctadiene iron tricarbonyl, 3-chloromethyl-l,5-cyclooctadiene ruthenium tricarbonyl, 3-cyclopentenyl-1,5-cyclooctadiene osmium tricarbonyl, 3,4-dimethyl-1,5cyclooctadiene iron tricarbonyl, 3-p-ethylphenyl 1,5 cyclooctadiene ruthenium tricarbonyl, 3,4-di-butyl-1,S-cyclooctadiene osmium tricarbonyl, and the like.

The compounds of this invention are produced by the reaction of a cyclooctadiene compound with a simple metal carbonyl of an iron-subgroup metal. A simple metal carbonyl is a compound composed solely of metal atoms and carbonyl groups. Typical simple metal carbonyls applicable in the process of this invention are iron pentacarbonyl, diiron enneacarbonyl, triiron dodecacarbonyl, ruthenium pentacarbonyl, diruthenium enneacarbonyl, triruthenium dodecacarbonyl, osmium pentacarbonyl and diosmium enneacarbonyl. In this reaction, the cyclooctadiene compound displaces carbon monoxide groups from the metal carbonyl reactant to form a cycleoctadiene metal carbonyl compound in which there are less carbonyl groups than were present in the original metal carbonyl reactant.

In general, the process may be carried out at temperatures between about to about 200 C. or higher. We have obtained good results at temperatures as high as about 225 C. Preferably, however, temperatures in the range from about to about C. are employed since, within this range, relatively higher yields are obtained with a minimum of undesirable side reactions. The pressure under which the process is carried out is not critical. Preferably, however, the process is conducted at atmospheric pressure or slightly higher although higher pressures,'up to 500 atmospheres, can be employed if desired. i

The process is generally conducted under-a blanketing atmosphere of an inert gas such as'nitrogen, helium, argon and the like.

The process'may be conducted in the presence of a nonreactive solvent. The nature of the solvent is not critical and, in fact, the cycl-ooctadiene reactant may in some cases be used in sufficient excess to serve as a reaction solvent.

, Typical of reaction solvents which may be employed in our process are high boiling saturated hydrocarbons I such as n-octane, n-decane, and other parafi'inic hydrocarbons having up to about 20 carbon atoms such as eicosane, pentadecane, and the like. Typical ether solvents are ethyl octyl ether, ethyl hexyl ether, diethyleneglycol methyl ether, diethyleneglycol diethyl ether, diethyleneglycol dibutyl ether, ethyleneglycol dimethyl ether, ethyleneglycol diethylether, trioxane, tetrahydrofuran, ethyleneglycol dibutyl ether and the like. Ester solvents which may be employed include pentyl butanoate, ethyl decanoate, ethyl hexanoate, and the like. Silicone oils such as the dimethyl polysiloxanes, bis(chlorophenyl) polysiloxanes, hexapropyldisilane, and diethyldipropyldiphenyldisilane may also be employed. Other ester solvents are those derived from succinic, maleic, glutaric, adipic, pirnelic, suberic, azelaic, sebacic and pinic acids. Specific examples of such esters aredi-(Z-ethylhexyl) adipate, di(2-etliylhexyl) azelate, di-(Z-ethylhexyl) sebacate, di-(methylcyclohexyl) adipate and the like. Of these enumerated solvents, those which are preferred for use in the process are the high boiling ethers and saturated aliphatic hydrocarbons. All of the above solvents will not be suitable for all'of the specific embodiments of the invention since certain of the metal carbonyl reactants are relatively insoluble in some of the above solvents. Thus, care should be used in selecting the specific solvent for the specific reaction.

The particular solvent employed in any embodiment of the process should be selected from those solvents having the requisite boiling and/or freezing point. Frequently the boiling point of the solvent is used to control the reaction temperature when the process is carried out at atmospheric pressure. In such cases, the reaction mixture is heated at reflux, and the reflux temperature is determined by the boiling point of the solvent. The ease of separating the product from the solvent depends on the degree of difference between the boiling and/ or freezing bonyl is obtained.

carbonyl employed.

points of the product and the solvent. If the product is a I liquid having a boiling point close to that of the solvent, it is obvious that separation will be diificult. In order to avoid this, it is preferableto select a solvent whose normal boiling point varies by at least 25 C. from the normal boiling point of a liquid product. If, on the other hand, the product is a solid, it is desirable that the freezing point of the solvent be at least 25 C. less than the temperature at which separation of the product is effected through crystallization. Obviously, if the solvent freezes before the solid product precipitates, it will be impossible to make a separation through crystallization.

The above criteria, as to physical properties of the sol- I vent, are not unique to this process. In any chemical process, it is necessary to pick a solvent whose physical properties make it readily separable from the product being formed. It is deemed, therefore, within the skill of the art to select the most suitable solvent for use in any particular embodiment of the process of the invention.

The process is preferably conducted with agitation of the reaction mixture. Although agitation is not critical to the success or failure of the process, its use is preferred since it accomplishes a smooth and even reaction rate.

V The time required for the process varies depending on the other reaction variables. In general, however, a time period from about two to about 24 hours is sufficient.

In some cases, the process is advantageously carried out in the presence of an ultraviolet light source. This tends to decrease the reaction time and give a higher yield of product.

In general, the metal'carbonyl reactant employed in the process is more expensive than the cyclooctadiene reactant. In order to insure maximum conversion of the metal carbonyl, it is, therefore, preferred to use excess quantities of the cyclooctadiene. Generally, from about one to about moles of a cyclooctadiene compound are employed for each mole of metal carbonyl reactant since, within this range, a good conversion of the metal car- In some cases, the cyclooctadiene reactant may be more expensive than the particular metal In these instances, excess carbonyl will be employed to insure complete conversion of the cyclooctad-iene compound.

In some cases, hydroquinone or other free radical reaction inhibitors can be employed in the reaction to prevent polymerization of the cyclooctadiene reactant. Their presence is not critical, however, to the success of the reaction. Typical of other applicable free radical inhibitors are p-tert-butyl catechol, p-hydroxy anisole, 4-amino-1- naphthol, chloranil, 2,4-dinitrochlorobenzene, dithiocarbamate and the like.

To further illustrate the compounds of the invention and their mode of preparation, there are presented the following examples in which all parts and percentages are by weight unless otherwise indicated.

Example 1 Triiron dodecacarbonyl, 3.4 parts, and approximately One mole of 3-methyl-1,S-cyclooctadiene and 0.1 mole of iron pentacarbonyl is heated at reflux for two hours under nitrogen. The reaction product is discharged from the reaction vessel and filtered; excess solvent is removed from the filtrate by heating under vacuum, and the residue is dissolved in low-boiling petroleum ether and chroma- (a, tographed on alumina. The eluate is heated in vacuo to remove the petroleum ether to yield 3-methyl-l,5-cyclooctadiene iron tricarbonyl. Similar results are obtained when diiron enneacarbonyl and triiron dodecacarbonyl are employed in place of iron pentacarbonyl in the above process.

Example III A solution comprising 0.25 mole of 2-ethyl-l,3-cyclooctadiene and 0.25 mole of diiron dodecacarbonyl dissolved in tetrahydrofuran is heated at reflux for 24 hours under nitrogen. The reaction product is filtered and solvent is removed from the filtrate by heating in vacuo. The residue is dissolved in low-boiling petroleum ether and chromatographed on alumina. On removing the solvent from the eluate by heating under vacuum, there is obtained Z-ethyl-1,3-cyclooctadiene iron tricarbonyl.

Example IV A solution comprising 0.5 mole of 1,5-cyclooctadiene and 0.25 mole of diruthenium enneacarbonyl dissolved in diethyl adipate is heated at reflux for 10 hours under nitrogen. The reaction product is filtered, and solvent is removed from the filtrate by heating in vacuo. There is obtained from the residue, by means of chromatographic separation as in the previous examples, 1,5-cyclooctadiene ruthenium tricarbonyl. Similar results are obtained when triruthenium dodecacarbonyl is employed in the process.

Example V A solution comprising 0.03 mole of 3-octyl-7-ethyl-L5- cyclooctadiene and 0.03 mole ofiron pentacarbonyl, dissolved in n-nonane, is heated at reflux for 14 hours under nitrogen. The reaction product is filtered;- solvent is removed from the filtrate by heating in vacuo, and the residue is dissolved in low'boiling petroleum ether and chromatographed on alumina. On removing the solvent from the eluate by heating under vacuum, there is obtained 3-octyl-7-ethyl-1,5-cyclooctadiene iron tricarbonyl.

Example VI A solution is formed by dissolving 0.03 mole of 2-cyclopropyl-1,5-cyclooctadiene and 0.03 mole of ruthenium pentacarbonyl in diethyleneglycol dimethylether. The resulting solution is heated, under nitrogen, for eight hours at reflux. The reaction product is filtered, and solvent is removed by heating in vacuo. There is obtained from the residue, by means of chromatographic separation, a good yield of a 2-cyclopropyl-1,5-cyclooctadiene ruthenium tricarbonyl compound.

Example VII A solution comprising 0.4 mole of 1,5-cyclooctadiene and 0.2 mole of osmium pentacarbonyl dissolved in diethyleneglycol dimethylether is heated at reflux for 12 hours under nitrogen. On filtration of the reaction product and removal of solvent by heating in vacuo, 1,5-cycl0- octadiene osmium tricarbonyl is obtained from the residue by means of chromatographic separation. Use of diosmium enneacarbonyl affords similar results.

Example VIII A solution comprising 0.2 mole of 3-et-hyl-l,5-cyclooctadiene and 0.2 mole of iron pentacarbonyl in diethyleneglycol dimethylether is heated at reflux under nitrogen for six hours. On filtration of the reaction product and removal of solvent by heating in vacuo, 3-ethyl-l,5-

'cyclooctadiene iron tricarbonyl is obtained from the residue by means of chromatographic separation. v

The compounds of this invention are useful antiknocks when added to a petroleum hydrocarbon. They may be used as primary antiknocks in which they are the major antiknock component in the fuel or as supplemental antiknocks. When used as supplemental antiknocks, they are present as the minor antiknock component in the fuel in addition to a primary antiknock such as a tetraalkyllead compound. Typical alkyllead compounds are tetraethyllead, tetrabutyllead, tetramethyllead and various mixed lead alkyls such as dimethyldiethyllead, diethyldibutyllead and the like. When used as either a supplemental or primary antiknock, our compounds may be present in the gasoline in combination with typical scavengers such as ethylene dichloride, ethylene dibromide, tricresylphosphate and the like.

The compounds are further useful in many metal plating applications. In order to effect metal plating using the compounds, they are decomposed in an evacuated space containing the object to be plated. On decomposition, they lay down a film of metal on the object. The gaseous plating may be carried out in the presence of an inert gas so as to prevent oxidation of the plating metal or the object to be plated during the plating operation.

The gaseous plating technique described above finds wide application in forming coatings which are not only decorative but also protect the underlying substrate material. When the metal is a conductor such as molybdenum, this technique enables the preparation of plated circuits which find wide application in the'electrical arts.

Deposition of metal on a glass cloth illustrates the applied process. A glass cloth band weighing one gram is dried for one hour in an oven at 150 C. It is then placed in a tube which is devoid of air and there is added to the tube 0.5 gram of 1,5-cyclooctadiene molybdenum tetracarbonyl. The tube is heated at 400 C. for one hour after which time it is cooled and opened. The cloth has a uniform metallic grey appearance and exhibits a gain in weight of about 0.02 gram. The cloth has greatly decreased resistivity and each individual fiber proves to be a conductor. An application of current to the cloth causes an increase in its temperature. Thus, a conducting cloth is prepared which can be used to reduce static electricity for decorative purposes, for thermal insulation by reflection and as a heating element.

The compounds may be added to distillate fuels such as are used in home heating, to jet engine fuels and also to diesel fuels. In these applications the compounds tend to reduce smoke and/ or soot formation on burning of the fuel. Also our compounds are useful additives to lubricant compositions where they act to improve the lubricity of the lubricant and reduce wear of the rubbing surfaces.

Some of the compounds of this invention are unstable and hence, quantitative microanalysis thereof is diflicult.

The following additional examples further illustrate the preparation of the novel compounds of this invention.

solved in about 29 parts of n-decane. The mixture was refluxed for 8 hours at 130 C, The resulting viscous mixture was filtered. The filtrate was distilled in vacuo and a small tarry residue was obtained. This residue was subjected to a short-path distillation onto a water-cooled probe at 2 mm. and at 50 C. A few drops of oil were collected on the probe. The infrared spectrum of this oil identified the product as 1,5-cyclooctadiene iron tricarbonyl.

Example X A mixture of 49 parts of iron pentacarbonyl, 30 parts of 1,5-cyclooctadiene, and a trace of hydroquinone was charged into an autoclave. The autoclave was pressured to 200 p.s.i. with nitrogen and the temperature slowly increased to 206 C. The temperature was then increased to 222 C. and the reaction vessel maintained at that temperature for two hours. Thereafter, the autoclave was cooled, vented, and discharged. The reaction mixture was distilled in vacuo and an oily residue was obtained. This oil was subjected to a spinning-band vacuum distillation. At 47 C. and at 2 mm. a small amount of a yellow oil distillate was collected. This oil was chromatographed on alumina using petroleum ether (3060 C.). The product .band Was eluted and the solvent removed by evaporation. The infrared spectrum and the elemental analysis of the residue indicated that it was 1,5-cyclooctadiene iron tricarbonyl. Calculated for C H FeO C, 53.3; H, 4.84; Fe, 22.6. Found: C, 54.5; H, 4.8; Fe, 24.4.

Having fully described the compounds, their mode of preparation and their many utilities, it is desired that the invention be limited only within the lawful scope of the appended claims.

This application is a continuation-in-part of application S.N. 68,587, filed November 14, 1960, now US. Patent No. 3,093,671, which in turn is a continuationin-part of application S.N. 862,065, filed December 28, 1959, and now abandoned.

We claim:

1. Organometallic compounds having the formula wherein Q is a cyclooctadiene molecule having up to about 18 carbon atoms and M is an iron subgroup metal.

2. Cyclooctadiene iron tricarbonyl.

3. A process for the preparation of a cyclooctadiene iron subgroup metal tricarbonyl compound, said process comprising reacting a cyclooctadiene having up to about 18 carbon atoms with a simple carbonyl of an iron subgroup metal.

4. The process of claim 3 wherein the reaction is carried out in the presence of an inert organic solvent.

5. The process of claim 4 wherein the reaction is carried out under a blanket of an inert gas.

No references cited. 

1. ORGANOMETALLIC COMPOUNDS HAVING THE FORMULA 